Refillable electric fuse



F. ci LA MAMND 9.1. HOPKINS..- REFILLABLEELECTRIC IUSEfY APPLICATION FILEDAUGIS, 19H3.

1 ,318,887 Panted 00u14, 1919 v UNITED sTATEjs PATENT oEEIcE.

'FRANK C. LA. MAR AND PETERJ. HOPKINS, 0F PITTSBURGH, PENNSYLVIA.

REFILLABLE ELECTRIC FUSE.

i Specification of Lettersatent.

Patented 0015.14, 1919.

Application filed August 16, 1918. Serial No 250,174.

United States of America, residing at Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a certain new and useful Improvement in Refillable' Electric Fuses, `of which the following is a full, clear, and exact description.

This invention relates to refillable or renewable electric fuses, wherein the fuse ele;

` ment or strip is inclosed in a tubular casing or shell and secured at its ends to anchoring devices iitted in or upon the ends of the casing, and held in place by `end caps or ferrules fitted on the ends of the casing.

The object of the invention is to provide a fuse of this type, of simple, economical and efficient construction, wherein the fuseelement anchoring or supporting devices and the end caps or ferrules are securely locked in place without extraneous fasten'- ing devices, and which may readily and quickly be assembled and as readily and quickly disassembled for removing a blown or disrupted fuse element and replacing it by a new one.

The invention consists in a reillable eleetric fuse, comprising a tubular casing, anchoring devices for supporting aA fuse element in said casing having means for locking them to the casing `against longitudinal movement or displacement and provided with a screwthreaded member projecting therefrom, and ferrules fitted upon the 'ends of the casing and provided with scrcwthreaded openings adapted to engage the screwthreaded members projecting from the anchoring devices, to thereby hold the anchoring devices in place and also securely bindthe fuse element to the anchoring devices to maintain good contact therebetween, all substantially as we will proceed now more particularly to set forth and finally claim.

In the accompanying drawings, illustrat-A ing the invention, in the several lignres of which like parts are similarly designated, Figure l is a side elevation of the assembled fuse. Fig. 2 is an elevation, with the end ferrnles removed. Fig. 8 is a vertical longitudinal section, showing the fuse element partly in elevation. F ig. i is a horizontal longitudinal section, taken substantially in the plane of line Ll--4f, Fig. 3, and looking in the direction of the arrpws. Fig. 5 is an end view of the right-hand end of Fig. 2. Fig. 6 is a section of one end of the fuse, showing a'modiied form of screw attachment for the 'anchoring devices. Fig. 7 is a section of one end of a fuse, showing another form of fuseelement anchoring and supporting device. Fig. 8 is a transverse'section, taken substantially in the plane of line 8 8, Fig. 7, and looking in the direction of the arrows. Fig. 9 is a detail view in elevation, showing a portion of another form of fuse element for use with the anchoring device shown in Figs. 7 and 8.. l

In the drawings, l represents the tubular casing of insulating material, provided at its opposite ends upon diametrieally opposite "sides with partially circumferential recesses or cut-away ,portions 2, terminating in partially circumferential grooves 3. Fitted upon the ends of the casing, are the fuseeelement supporting and anchoring devices, and as shown in Figs. 2 to 5, these anchoring devices comprise disks 4, provided with slots 5 for receiving the ends of the fuse element 6, and a centrally arranged screw 7, made integral with the disks, as shown in said figures, or which may be a separate screw, as shown at 8, Fig. 6, and over ing devices are locked on the ends of the casing against longitudinal movement.

kIn order to bind the ends 9 of the fuse element into good contact with the anchoring disks 4, and also to confine the said disks in place upon the ends of the casing, end caps or ferrnles l2, having plane or Unthreaded body portions and centrally arranged screwthreaded openings 13 in their ends, are fitted upon the ends of the casing, the said screwthreaded openings 13 engaging the projecting screws 7 of the disks 4, and the ferrules adapted te be rotated to draw them upon the ends of the casing over the extensions 2 of the anchoring devices, the inner surfaces of the. ends of Ithe `errules engaging the bent ends ot the fuse element and holding them in rood Contact with the disks il.,

s herein. shown7 the end caps or ferrules 12 are provided with squared portions 12 to receive a wrench for turning;` theni oit in case they become too tight to be removed byI hand. However, the squared portions may be omitted ln 7 and 8 the invention shown applied to another torni of `fuse-element anchoring device, and in this torni ot the dcvice, the anchoring device is constructed similarly to the anchoring device shown in Figs. 2 to 5, but instead ot the disks 1 being provided with the tosc-element engaging slot, it is provided with an inwardly extending;v boss 1&1, having' an outwardlyv tapering,- or conical bore 15, and fitted in said boss is a fuse-elenient engagingl clutch, comprising` a radially slitted conical block 16 having a centrally arranged opening,` 17 to receive the end ot a straight wire fuse 18, as in Fig. 7, or a flat strip fuse 19, as shown in 9. The clutch block 1G is provided at its outer end with a s .'1'ewthre:uled projcction 20 extending beyond the end ot the disk, and adapted to be engaged by the screwthreaded openings in the end ot the caps or ferrules 12, whereby when the ferrules are turned to place upon the ends of the casing, the clutch blocks will be drawn into the taperingl or conical bore ot the boss 1l, to thereby contract the slotted or slitted end of the clutch block and securely bind the ends ot' the 'fuse element Vin the clutch blocks.

ln order to tix the clutch blocks 1G in the boss 14 against displacement, the said clutch blocks are provided with a longitudinal groove 21 extending from its inner end to within a short distance ot' its outer end, and a pin passing through the end of the boss and proj eetinp, into the groove 21, and which is adapted to engage the inner end of the groove 21 to prevent the removal ot' the clutch block from the boss. said pin and groove connection also serving to prevent rotation of the clutch in the boss, when the end caps or terrulis are. screwed to place, and thereby avoid twisting and breaking' the tuse element when assembling the, rinse.

ln Figs. 'l and S, the, inwardly extending.

portions of the anchoring" devices are shown ot less width than thosey inthe other 1.,ures,`

but these parts may be constructed of any desired width around the periphery ot' the disks ot the anchoring devices sufficient to serve the purpose ot' the invention.

ln assembling` the lnse. the anchoring devices are placed upon the ends ot the casing1 and the ends ol' the fuse element fixed thereto as above described, and the. end caps or t'errnles fitted upon the ends of the easing and screwed up tight, thus firmly and seleises? curely binding the ends ot the fuse element in contact with the anchoring devices, and thus the parts are securely locked in place against displacement by a blow-out or explosion of the fuse, without extraneous or separate fastening` devices, the end caps or ierrules being' provided with the usual opening Q3, see l, torI the escape of the gases due to a blow-out or explosion oit the Yfuse element.

'W hen the fuse is blown or disrupted, and it is desired to replace the damaged fuse element by a new one, it is simply necessary to remove the cnd caps or 'errules by unserewing` them and take oill the anchoring devices, and the parts of the damaged fuse element may then be removed from the anchoring1 devices, and the fuse then renewed or rclilled with a new fuse element by assembling the parts as hereinbefore explained,

lt is to be understood, that the invention is not limited to the exact details of construction herein shown and described, as the same may be changed in various particulars and still be within the scope of the appended claims, and also that the invention is not limited to its applicability to the two forms oit fuse-element anchoring devices herein shown, as it is equally applicable to other well known terms of fuse-element anchoring devices.

lWhat we claim is 1. fr relillable electric fuse, comprising a tubular casing of insulating material, having partial circum'terential peripheral grooves near its ends, fuse-element anchoring devices litted on the ends of the casing', each provided with an inwardly extendine' portion overlying the end of the casing and adapted to engage the groove in the end of the casing' and a screwthreaded portion projecting from the outer tace thereof, and terrules havingl plane or unthreaded body portions and adapted to be fitted upon the ends of the casing over the inwardly extending portions ot the anchoring devices and provided with screwthreaded openings in their end walls adapted to engage the screvvtlneadedprojections on the fuse-elcment anchoring` devices for locking the parts in place.

2. li retillahle electric fuse, comprising a tubular casing' of insulating` material, having cut-away portions at its ends terminating' in eircuinterential p'rooves, fuse-element anchoring devices titted on the ends of the casiiner and provided with inwardly extending,- portions fitting' in said eut-away portions ot the casing, and terminating in inwardly projectingr flanges entering the circumferential ,grooves in the easin, and sc1e\\'tluea(le l members projecting from the outer faces ot' the fuse-element anchor'- ing devices, and terrules adapted to fit upon the ends of the casing over the `iengedinwerdly extending `portions of the fuse-e1e ment'anchoring devices `sind provided With screw-threaded openings in -their ends adapted to engage the sorewthreeded projections on the anchoring devices -for looklng the parts in place.

In testimony whereof, We have hereunto` set our hands this 13th day onf August 1918, at Pittsburgh, Pe.

FRANK o. LA MAR. P, J. HOPKINS.

Witnesses:

N. E. CRITGHLOW, S. P. GORDON. 

